Apparatus and method for reducing turbulence of airflow in a hard disk drive

ABSTRACT

A sickle-shaped disk drive spoiler for reducing turbulence of airflow in a hard disk drive is provided. The sickle-shaped spoiler includes a body portion for directing airflow generated by a rotating disk, the rotating disk comprising an inner diameter and an outer diameter and wherein the body portion of the spoiler directs airflow away from the outer diameter of the disk and wherein the body portion is curved to substantially mirror the outer diameter of the disk. The sickle-shaped spoiler also includes a first end portion for gradually directing airflow away from the body portion and towards the inner diameter and a second end portion for gradually directing airflow towards the body portion and towards the inner diameter.

TECHNICAL FIELD

The present invention relates to the field of hard disk drives, and moreparticularly to an apparatus and method for reducing turbulence ofairflow in a hard disk drive.

BACKGROUND ART

Hard disk drives are used in almost all computer system operations. Infact, most computing systems are not operational without some type ofhard disk drive to store the most basic computing information such asthe boot operation, the operating system, the applications, and thelike. In general, the hard disk drive is a device which may or may notbe removable, but without which the computing system will generally notoperate.

The basic hard disk drive model was established approximately 50 yearsago and resembles a phonograph. That is, the hard drive model includes astorage disk or hard disk that spins at a standard rotational speed. Anactuator arm or slider is utilized to reach out over the disk. The armhas a magnetic read/write transducer or head for reading/writinginformation to or from a location on the disk. The complete assembly,e.g., the arm and head, is called a head gimbal assembly (HGA).

In operation, the hard disk is rotated at a set speed via a spindlemotor assembly having a central drive hub. Additionally, there aretracks evenly spaced at known intervals across the disk. When a requestfor a read of a specific portion or track is received, the hard diskaligns the head, via the arm, over the specific track location and thehead reads the information from the disk. In the same manner, when arequest for a write of a specific portion or track is received, the harddisk aligns the head, via the arm, over the specific track location andthe head writes the information to the disk.

Over the years, the disk and the head have undergone great reductions intheir size. Much of the refinement has been driven by consumer demandfor smaller and more portable hard drives such as those used in personaldigital assistants (PDAs), MP3 players, and the like. For example, theoriginal hard disk drive had a disk diameter of 24 inches. Modern harddisk drives are much smaller and include disk diameters of less than 2.5inches (micro drives are significantly smaller than that). Advances inmagnetic recording are also primary reasons for the reduction in size.

A second refinement to the hard disk drive is the increased efficiencyand reduced size of the spindle motor spinning the disk. That is, astechnology has reduced motor size and power draw for small motors, themechanical portion of the hard disk drive can be reduced and additionalrevolutions per minute (RPMs) can be achieved. For example, it is notuncommon for a hard disk drive to reach speeds of 15,000 RPMs. Thissecond refinement provides weight and size reductions to the hard diskdrive, it also provides a faster read and write rate for the diskthereby providing increased speed for accessing data. The increase indata acquisition speed due to the increased RPMs of the disk drive andthe more efficient read/write head portion provide modern computers withhard disk speed and storage capabilities that are continuallyincreasing.

However, the higher RPMs of the disk has resulted in problems withrespect to the interaction of the air with components of the hard diskdrive. For example, although the hard disk drive is closed off from theoutside, it has an amount of air within its packaging. As the disk spinsand the RPMs increase, the air within the hard disk drive package willalso begin to rotate and will eventually approach the speed at which thedisk is rotating especially near the spindle hub and disk surfaces. Thisis due to the friction between the disk and the air. In general,Reynolds numbers are used to represent the flow characteristics. Forexample, in one case the Reynolds number may be based on the tip speedof the disk, that is, the linear velocity at the outer diameter of thedisk, the disk diameter or other characteristic length scale, and thekinematic viscosity of the air.

Only when the Reynolds number is sufficiently small (e.g., an enclosurewith reduced air density), the air may stay in laminar flow with theboundary layer of air remaining smooth with respect to the rotatingdisk. However, any obstructions to the flow will result in turbulence.That is, due to the introduction of obstructions to the airflow, theairflow will become turbulent as it passes the obstruction. Usually, theReynolds number is so large that the airflow is turbulent near the diskrim, even where the arm is loaded onto a load/unload ramp.

As is well known from fluid mechanics, the characteristics of turbulentairflow can lead to buffeting, harmonic vibration, and the like. Each ofthese characteristics will result in problematic motion for the arm andhead portion and/or the rotating disk. The problematic motion willresult in excessive track misregistration. This is even more significantas the track pitch of the tracks on hard disks is further reduced.

SUMMARY

A sickle-shaped disk drive spoiler for reducing turbulence of airflow ina hard disk drive is provided. The sickle-shaped spoiler includes a bodyportion for directing airflow generated by a rotating disk, the rotatingdisk comprising an inner diameter and an outer diameter and wherein thebody portion of the spoiler directs airflow away from the outer diameterof the disk and wherein the body portion is curved to substantiallymirror the outer diameter of the disk. The sickle-shaped spoiler alsoincludes a first end portion for gradually directing airflow away fromthe body portion and towards the inner diameter and a second end portionfor gradually directing airflow towards the body portion and towards theinner diameter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic, top plan view of a hard disk drive in accordancewith one embodiment of the present invention.

FIG. 2 is a diagram of an exemplary disk drive disk and a sickle-shapedspoiler for reducing air turbulence in accordance with embodiments ofthe present invention

FIG. 3 is a top view of an exemplary sickle-shaped spoiler with a bodyportion that tapers in width from a middle portion to end portions inaccordance with embodiments of the present invention

FIG. 4 is a top view of an exemplary sickle-shaped spoiler that tapersfrom a width at a first end to a point at a second end in accordancewith embodiments of the present invention.

FIG. 5 is a top view of an exemplary two piece sickle-shaped spoiler inaccordance with embodiments of the present invention.

FIG. 6 is a flow diagram of an exemplary method for reducing turbulenceof airflow in a hard disk drive in accordance with embodiments of thepresent invention.

BEST MODES FOR CARRYING OUT THE INVENTION

Reference will now be made in detail to the alternative embodiment(s) ofthe present invention, an apparatus and method for reducing turbulenceof airflow in a hard disk drive. While the invention will be describedin conjunction with the alternative embodiment(s), it will be understoodthat they are not intended to limit the invention to these embodiments.On the contrary, the invention is intended to cover alternatives,modifications and equivalents, which may be included within the spiritand scope of the invention as defined by the appended claims.

Furthermore, in the following detailed description of the presentinvention, numerous specific details are set forth in order to provide athorough understanding of the present invention. However, it will berecognized by one of ordinary skill in the art that the presentinvention may be practiced without these specific details. In otherinstances, well known methods, procedures, components, and circuits havenot been described in detail as not to unnecessarily obscure aspects ofthe present invention.

With reference now to FIG. 1, a schematic drawing of one embodiment ofan information storage system 100 comprising a magnetic hard disk fileor drive 111 for a computer system is shown. Drive 111 has an outerhousing or base 113 containing a disk pack having at least one media ormagnetic disk 115. The disk or disks 115 are rotated (see arrows 141) bya spindle motor assembly having a central drive hub 117. An actuator 121comprises a plurality of parallel actuator arms 125 (one shown) in theform of a comb that is movably or pivotally mounted to base 113 about apivot assembly 123. A controller 119 is also mounted to base 113 forselectively moving the comb of arms 125 relative to disk 115. The aircirculation in the device 100 is handled by full bypass 150.

In the embodiment shown, each arm 125 has extending from it at least onecantilevered load beam and suspension 127. A magnetic read/writetransducer or head is mounted on a slider 129 and secured to a flexurethat is flexibly mounted to each suspension 127. The read/write headsmagnetically read data from and/or magnetically write data to disk 115.The level of integration called the head gimbal assembly (HGA) is headand the slider 129, which are mounted on suspension 127. The slider 129is usually bonded to the end of suspension 127. The head is typicallypico size (approximately 1160×1000×300 microns) and formed from ceramicor intermetallic materials. The head also may be of “femto” size(approximately 850×700×230 microns) and is pre-loaded against thesurface of disk 115 (in the range two to ten grams) by suspension 127.

Suspensions 127 have a spring-like quality, which biases or urges theair-bearing surface of the slider 129 against the disk 115 to cause theslider 129 to fly at a precise distance from the disk. A voice coil 133free to move within a conventional voice coil motor magnet assembly 134(top pole not shown) is also mounted to arms 125 opposite the headgimbal assemblies. Movement of the actuator 121 (indicated by arrow 135)by controller 119 moves the head gimbal assemblies along radial arcsacross tracks on the disk 115 until the heads settle on their respectivetarget tracks. The head gimbal assemblies operate in a conventionalmanner and always move in unison with one another, unless drive 111 usesmultiple independent actuators (not shown) wherein the arms can moveindependently of one another.

Referring still to FIG. 1, the disk pack and disks 115 (one shown)define an axis 140 of rotation 141 and radial directions 142,143,relative to the axis 140. The drive 111 also has a bypass channel 150formed in the housing 113 for directing the airflow 160 generated byrotation of the disks 115 from the upstream side of the disk pack ordisks (e.g., proximate to radial direction 142 in FIG. 1) 115 to thedownstream side of the disk pack or disks 115 (e.g., proximate to radialdirection 143 in FIG. 1). FIG. 1 shows a sickle-shaped spoiler 170 inaccordance with embodiments of the present invention. In one embodiment,the sickle-shaped spoiler 170 is located opposite the actuator 121 togradually direct airflow towards the inner diameter of the disk 115.

In the embodiment shown, the bypass channel 150 is located between anouter perimeter 116 of the housing 113 and the actuator 121, such thatthe bypass channel 150 completely circumscribes the actuator 121. Bypasschannel 150 further comprises a first opening 151 proximate to upstreamside wherein air is conveyed away from the disks 115 and a secondopening 152 proximate to downstream side wherein airflow 160 is directedtoward the disks 115.

As shown in FIG. 1, one embodiment of the drive 111 bypass channel 150also comprises a diffuser 153. In the embodiment shown, the diffuser 153is located in the bypass channel 150 and is positioned adjacent to theupstream side of the disk pack or disks 115. The diffuser 153 is alsooffset upstream from the disks 115 in the radial direction 142, suchthat the diffuser 153 reduces airflow drag from the disks 115 due todisk wake in the bypass channel 150. This type of aerodynamic drag iscommonly called base drag.

Alternatively, or operating in conjunction with the diffuser 153,another embodiment of the drive 111 may include a contraction 154 (e.g.,inlet to a Venturi). The contraction 154 is also located in the bypasschannel 150, but is adjacent to the downstream side of the disk pack ordisks 115. Like the diffuser 153, the contraction 154 is typicallyoffset downstream from the disks 115, but in a radial direction 143.Each of the diffuser 153 and the contraction 154 may be spaced apartfrom the outer edges of the disks 115 in radial directions 142,143 by,for example, approximately 0.5 mm. The contraction 154 may be providedfor re-accelerating bypass airflow 160 to provide efficient energyconversion for the air flow from pressure energy to kinetic energy priorto merging bypass airflow 160 with air flow 141 around the disks 115.

In embodiments of the present invention, disk drive system 111 may befilled with a gas (e.g., helium) rather than ambient air. This may beadvantageous in that helium is a lighter gas than ambient air and causesless buffeting of actuator 121 when disk drive system 111 is inoperation. In embodiments of the present invention, disk drive 111 maybe sealed after the servo writing process to keep the helium in thedrive. Alternatively, the helium may be removed from disk drive 111 andambient air is allowed to return into the disk drive prior to sealingfirst opening 151 and second opening 152.

Sickle-Shaped Spoiler for Reducing Turbulence of Air in a Disk Drive

Embodiments of the present invention include a sickle-shaped spoilerdesign to reduce turbulence of air in a hard disk drive. In oneembodiment of the invention, the spoiler is sickle-shaped to enablegradual radial deflection of airflow. In one embodiment, thesickle-shaped spoiler reduces air turbulence without increasing motortorque. The sickle-shaped spoiler also shields the arm from high airspeed air flow in one embodiment. The spoiler also reduces airturbulence, especially near the outer diameter (OD) of the rotatingdisks. Furthermore, embodiments of the present invention include amounting system incorporated into the sickle-shaped spoiler for improvedmanufacturing.

Embodiments of the present invention are directed to reducing trackmisregistration (TMR) associated with a disk drive. TMR is a well knownmeasurement in the art that quantifies how much the read/write head ofthe disk drive is “off track.” TMR is often described as a percentage ofthe drive's track pitch or can be described in absolute distance terms(nanometers). Airflow turbulence is a factor that contributes to TMR.

In particular, airflow at the outer diameter of the disk impactsmovement of the disk more than airflow at the inner diameter of thedisk. Embodiments of the present invention direct airflow away from theouter diameter of the disk and towards the inner diameter of the disk toreduce airflow turbulence and hence reduce TMR.

FIG. 2 is a diagram 200 of an exemplary disk drive disk 115 and asickle-shaped spoiler 250 for reducing air turbulence in a disk drive111 in accordance with embodiments of the present invention.

In FIG. 2, the sickle-shaped spoiler 250 is a partial moon shape withtapered end portions. In one embodiment, the tapered end portions enablegradual deflection of airflow. In one embodiment, the sickle shapedspoiler 250 directs airflow away from the outer diameter 290 of the disk115 towards the inner diameter 280 of the disk 115.

Airflow is generated by rotation 141 of disk 115. The speed of theairflow between the spoiler 250 and the inner diameter 280 is increasedwhile airflow on the opposite side of the disk 115 (with respect to thespoiler 250) is reduced. It is appreciated that many differentconfigurations of a sickle-shaped spoiler can be used in accordance withembodiments of the invention.

It is appreciated that the sickle-shaped spoiler 250 is curved toapproximately mirror the outer diameter 290 of the disk 115. It is alsoappreciated that the end portions of the sickle-shaped spoiler may ormay not be symmetrical with respect to each other.

The terms “inner diameter” and “outer diameter” are intended to be forillustrative purposes only. The term inner diameter referrers to aportion of the disk that is inside of the outer diameter of the diskwith respect to the middle of the disk.

It is appreciated that the sickle-shaped spoiler of the presentinvention can include perforations, and/or surface contours to furtherimprove the spoiler design. For example, a perforation through thespoiler perpendicular to the surface of the disk may reduce particleaccumulation on the disk surface. It is appreciated that many surfacecharacteristics of the spoiler can be used in accordance withembodiments of the present invention.

FIG. 3 is a top view of an exemplary sickle-shaped spoiler 300 with abody portion 302 that tapers in width from a middle width 375 to endportions 310 and 320 in accordance with embodiments of the presentinvention. In this embodiment, the spoiler 300 has a circumferentiallength 362 (on the outside diameter side 318) that is greater than halfthe circumferential length of the disk (not shown).

In one embodiment, the body portion 302 directs airflow away from theouter diameter side 319. In one embodiment, end portion 310 directsairflow away from the body portion 302 and increases air flow toward theinner diameter of the disk. In another embodiment, end portion 320directs airflow away from the body portion 302 and increases air flowtoward the inner diameter of the disk.

It is appreciated that the curve of the sickle-shaped spoiler 300roughly mirrors the curve of the disk (not shown) such that the outerdiameter edge 319 of the spoiler 300 approximately aligns with the outerdiameter edge of the disk.

In this embodiment, the width of end portion 320 tapers to a point wherethe outer diameter side 319 of the spoiler meets the inner diameter side318 of the spoiler 300.

The width of end portion 310 also tapers to a point where the outerdiameter side 319 of the spoiler meets the inner diameter side 318 ofthe spoiler 300. Spoiler 300 also includes attachment points 350.

Attachment points 350 are integrated into the spoiler 300 to enableattachment of the spoiler 300 in a disk drive. Because of theirflexibility, the sickle shaped spoilers of the present invention can bemounted in a simple way. As implied by their name, sickle spoilers ofthe c-ring type can be secured by bending in their plane.

While distorted, the spoiler 300 can be inserted into place and once inplace, the distortion provides enough force (tensile or compression) tokeep the spoiler in the desired location. In one embodiment, the spoiler300 is self mounting and does not require screws or adhesive to bemounted securely.

The spoiler 300 of FIG. 3 includes a tapered design wherein the spoilerwidth tapers from a middle width 375 to points on each end 320 and 310.The gradual taper in width enables a gradual deflection of airflow whichreduces turbulence of airflow in a disk drive.

FIG. 4 is a top view of an exemplary sickle-shaped spoiler 400 thattapers in width from width 475 at a first end 470 to a point at a secondend 480 in accordance with embodiments of the present invention. In thisembodiment, spoiler 400 directs airflow from the outer diameter side 319towards the inner diameter side 318.

FIG. 5 is a top view of an exemplary two piece sickle-shaped spoiler 500in accordance with embodiments of the present invention. In thisembodiment, two sickle shaped spoilers 510 and 520 are used. However, itis appreciated that any number of sickle-shaped spoilers could be usedin accordance with the present invention. Sickle-shaped spoilers 510 and520 could be any shape as described in FIGS. 2-4 or any othersickle-shape.

Spoiler 510 tapers in width 515 from a first end 521 to a second end522. The spoiler 510 directs airflow from the outer diameter side 519 tothe inner diameter side 518.

Spoiler 520 tapers in width 540 from a first end 541 to a second end542. The spoiler 520 directs airflow from the outer diameter side 519 tothe inner diameter side 518.

It is appreciated that the space 599 between spoiler 510 and 520 may bethe location of an actuator arm (not shown) wherein one spoiler is“upstream” from the actuator arm and the other is “downstream” of theactuator arm.

FIG. 6 is a flow diagram of an exemplary method 600 for reducingturbulence of airflow in a hard disk drive in accordance withembodiments of the present invention.

At 602, 600 includes providing a body portion for directing airflowgenerated by a rotating disk, the rotating disk comprising an innerdiameter and an outer diameter wherein the body portion directs airflowaway from the outer diameter of the disk and wherein the body portion iscurved to substantially mirror the outer diameter of the disk.

At 604, 600 includes providing a first end portion for graduallyreducing airflow away from the body portion and towards the innerdiameter.

At 606, 600 providing a second end portion for gradually increasingairflow towards the body portion and towards the inner diameter.

The alternative embodiment(s) of the present invention, a method andsystem for reducing particle accumulation on a disk surface in a harddisk drive, is thus described. While the present invention has beendescribed in particular embodiments, it should be appreciated that thepresent invention should not be construed as limited by suchembodiments, but rather construed according to the below claims.

1. A sickle-shaped disk drive spoiler comprising: a body portion fordirecting airflow generated by a rotating disk, said rotating diskcomprising an inner diameter and an outer diameter wherein said bodyportion directs airflow away from said outer diameter of said disk andwherein said body portion is curved to substantially mirror said outerdiameter of said disk; a first end portion for gradually directingairflow away from said body portion and towards said inner diameter; anda second end portion for gradually directing airflow towards said bodyportion and towards said inner diameter.
 2. The disk drive spoiler asdescribed in claim 1 wherein said first end portion gradually tapers toa point to enable gradual direction of airflow away from said bodyportion and towards said inner diameter.
 3. The disk drive spoiler asdescribed in claim 1 wherein said second end portion gradually tapers toa point to enable gradual direction of airflow towards said body portionand towards said inner diameter.
 4. The disk drive spoiler as describedin claim 1 wherein said body portion, said first end portion or saidsecond end portion comprise perforations perpendicular to said rotatingdisk.
 5. The disk drive spoiler as described in claim 1 wherein saidfirst end portion or said second end portion comprises an attachmentmechanism for mounting said spoiler proximate said rotating disk suchthat said spoiler is stationary with respect to said rotating disk. 6.The disk drive spoiler as described in claim 1 wherein an outer diameterside circumferential length of said spoiler is greater than half thecircumference of said rotating disk.
 7. The disk drive spoiler asdescribed in claim 1 wherein said first end portion is asymmetrical withsaid second end portion.
 8. A hard disk drive comprising: a housing; adisk pack mounted to the housing and having a plurality of disks thatare rotatable relative to the housing, the disk pack defining an axis ofrotation and a radial direction relative to the axis, said diskscomprising an inner diameter and an outer diameter; an actuator mountedto the housing and being movable relative to the disk pack, the actuatorhaving a plurality of heads for reading data from and writing data tothe disks; and a plurality of spoilers, at least one spoilersickle-shaped and comprising: a body portion for directing airflow awayfrom said outer diameter of said disk and wherein said body portion iscurved to substantially mirror said outer diameter of said disk; a firstend portion for gradually directing airflow away from said body portionand towards said inner diameter; and a second end portion for graduallydirecting airflow towards said body portion and towards said innerdiameter.
 9. The disk drive as described in claim 8 wherein said firstend portion of said sickle-shaped spoiler gradually tapers to a point toenable gradual direction of airflow away from said body portion andtowards said inner diameter.
 10. The disk drive as described in claim 8wherein said second end portion of said sickle-shaped spoiler graduallytapers to a point to enable gradual direction of airflow towards saidbody portion and towards said inner diameter.
 11. The disk drive asdescribed in claim 8 wherein said body portion, said first end portionor said second end portion of said sickle-shaped spoiler compriseperforations perpendicular to said rotatable disks.
 12. The disk driveas described in claim 8 wherein said first end portion or said secondend portion of said sickle-shaped spoiler comprises an attachmentmechanism for mounting said spoiler proximate one of said rotatabledisks such that said spoiler is stationary with respect to saidrotatable disks and wherein said attachment mechanism utilizes acompression force or tensile force of said spoiler to enable saidmounting.
 13. The disk drive as described in claim 8 wherein acircumferential length of said spoiler is greater than half thecircumference of one of said rotatable disks.
 14. The disk drive asdescribed in claim 8 wherein said first end portion is asymmetrical withsaid second end portion.
 15. A method for reducing turbulence of airflowin a hard disk drive comprising: providing a body portion for directingairflow generated by a rotating disk, said rotating disk comprising aninner diameter and an outer diameter wherein said body portion directsairflow away from said outer diameter of said disk and wherein said bodyportion is curved to substantially mirror said outer diameter of saiddisk; providing a first end portion for gradually directing airflow awayfrom said body portion and towards said inner diameter; and providing asecond end portion for gradually directing airflow towards said bodyportion and towards said inner diameter.
 16. The method as described inclaim 15 wherein said first end portion gradually tapers to a point toenable gradual direction of airflow away from said body portion andtowards said inner diameter.
 17. The method as described in claim 15wherein said second end portion gradually tapers to a point to enablegradual direction of airflow towards said body portion and towards saidinner diameter.
 18. The method as described in claim 15 wherein saidbody portion, said first end portion or said second end portion compriseperforations perpendicular to said rotating disk.
 19. The method asdescribed in claim 15 wherein said first end portion or said second endportion comprises an attachment mechanism for mounting said spoilerproximate said rotating disk such that said spoiler is stationary withrespect to said rotating disk.
 20. The method as described in claim 15wherein a circumferential length of said spoiler is greater than halfthe circumference of said rotating disk.
 21. The method as described inclaim 15 wherein said first end portion is asymmetrical with said secondend portion.